1. Field of the Invention
The present invention relates generally to a wireless mobile communication system based on an Internet Protocol (IP), and in particular, to a system and method for paging at high speed in an IP-based wireless mobile communication system.
2. Description of the Related Art
The wire and wireless communication systems are currently evolving into the next generation mobile communication system in which wire/wireless, voice, data and multimedia services are integrated over the Internet. The next generation mobile communication system aims at an ALL IP-based network configuration for combining computers and communication, with the rapid increase in Internet traffic and the development of communication technology.
If there is no data traffic to transmit/receive for a predetermined time, a mobile station (MS) of the next generation mobile communication system operates in an idle mode to minimize power consumption. The MS sends a message indicating start of the idle mode to a base station (BS), and the BS or a paging controller traces and registers a position of the MS operating in the idle mode. A description will now be made of an MS operating in the idle mode in, for example, an Institute of Electrical and Electronics Engineers (IEEE 802.16) communication system.
To operate in the idle mode, the MS sends a De-Registration Request (DREG-REQ) message to a serving BS with which it is currently communicating. Upon receipt of the DREG-REQ message, the serving BS sends a De-Registration Command (DREG-CMD) message to the MS to authorize operation in the idle mode. Tables 1 and 2 below show formats of the DREG-REQ and DREG-CMD messages, respectively.
TABLE 1SizeSyntax(bits)NotesDREG-REQ message——formatManagement message type8—= 49De-80 x 00 = MSS De-Registration request from BSRegistration_Request_Code0 x 01 = request for MS De-Registrationfrom serving BS and initiation of MS IdleMode0 x 02 = Response for the Unsolicited MSDe-Registration initiated by the BS.0 x 0 + 3 − 0 x FF = ReservedTLV encoded parametersvariable—}——
TABLE 2SyntaxSizeNotesDREG-CMD_Message_FormatManagement Message Type =8 bits29Action Code8 bitsTLV encoded parametersvariable}
The MS requests an operation corresponding to a De-Registration_Request_Code value of the DREG-REQ message, and the serving BS requests or responds (authorizes) an operation corresponding to an Action Code value of the DREG-CMD message. The serving BS may use an unsolicited message as opposed to the DREG-CMD message, without having to receive the DREG-REQ message. For example, if the MS sets the De-Registration_Request_Code value of the DREG-REQ message to ‘01’ before transmission, it indicates a transition request to the idle mode. If the serving BS sets the Action Code value of the DREG-CMD message to ‘05’ before transmission, the MS transitions to the idle mode.
‘Type/Length/Value (TLV) encoded parameters’ fields of the DREG-REQ and DREG-CMD messages include a variety of parameter information, such as paging-related fields.
FIG. 1 is a diagram illustrating a paging service configuration in a conventional IEEE 802.16e communication system.
Referring to FIG. 1, neighbor cells can constitute one logical group according to their geographical location. A paging controller (PC) 120 assigns a Paging Identifier (PG_ID) to each logical paging group composed of a plurality of cells. The PC 120 may be included in a BS, or in another network entity. In FIG. 1, the cells are divided into four paging groups of PG_ID#1 130a, PG_ID#2 130b, PG_ID#3 130c and PG_ID#4 130d, and the paging groups are managed by the PC 120.
It is assumed that an MS 150 is now communicating with a serving BS 140a in the idle mode. In this case, all BSs belonging to the PG_ID#1 130a, or the PC 120 can page the MS 150. That is, if the MS 150 is located in coverage of the PG_ID#1 130a, it can receive a paging service from the PC 120 or the BSs belonging to the PG_ID#1 130a. When the MS 150 operating in the idle mode moves from an previous (old) paging group (i.e. PG_ID#1) to another (new) paging group (i.e. PG_ID#2), there are several schemes for recognizing the movement. One such scheme is receiving a Downlink Channel Descript (DCD) message, and another such scheme is receiving a Mobile Paging Advertisement (MOB_PAG-ADV) message. The following description will be made with reference to the MOB_PAG-ADV message.
FIG. 2 is a diagram illustrating a paging operation in a conventional IEEE 802.16e communication system.
Referring to FIG. 2, BS#1 210, BS#2 220, BS#3 230 and BS#4 240 belong to PG#1 280, and BS#3 230, BS#4 240, BS#5 250 and BS#6 260 belong to PG#2 290. An MS 200 is located in a coverage area of the BS#3 230, and in the overlapping coverage area of the PG#1 280 and the PG#2 290.
If there is any packet data to transmit to the MS 200, PC#1 270 sends a MOB_PAG-ADV message to all MSs of PG#1 280 and PG#2 290. PC#1 270 pre-stores a Medium Access Control (MAC) address of the MS 200, a Home of Address (HoA), and information on the paging group to which the MS 200 belongs, and can communicate with the MS 200 using such information.
FIG. 3 is a flowchart illustrating a location update process performed by an MS in a conventional IEEE 802.16e communication system.
Referring to FIG. 3, in step 302, the MS operates in the idle mode through an exchange of a DREG-REQ message and a DREG-CMD message with a serving BS. In step 304, the MS receives a MOB_PAG-ADV message or a DCD message including PG_ID information. In step 306, the MS detects the PG_ID information included in the MOB_PAG-ADV message or the DCD message, and compares the detected new PG_ID information with its old PG_ID information. If the old PG_ID is different from the new PG_ID, the MS proceeds to step 308, recognizing a change in paging group. However, if there is no change in the paging group, the MS re-performs step 302 and its successive steps. Table 3 below shows a format of the MOB_PAG-ADV message.
TABLE 3SizeSyntax(bits)NotesMOB_PAG-ADV_Message_Format( )——{Management Message Type = 628—Num_Paging_Group_IDs8Number of Paging Group IDs in thismessageFor(i = 0;i < Num———Paging_Group_IDs;i ++){Paging Group ID8—}——Num_MACs8Number of MS MAC addressesFor(j = 0;j < Num_MACs;j ++) {——MS MAC Address hash24The hash is obtained by computingCRC24 on the MS 48-bit MACaddress. The polynomial for thecalculation is 0 x 864CFBAction Code2 bitPaging action instruction to MS0b00 = No Action Required0b01 = Perform Ranging to establishlocation and acknowledge message0b10 = Enter Network0b11 = reservedReserved6—}——paddingVariablePadding bits to ensure octet alignedTLV Encoded InformationVariableTLV specific}——
In step 308, the MS sends a Ranging Request (RNG-REQ) message for location update to the newly recognized serving BS. In step 310, the MS receives a Ranging Response (RNG-RSP) message from the serving BS. In step 312, the MS determines whether a Location Update Response field in a TLV encoded information field of the RNG-RSP message indicates success in location update. If the Location Update Response field is set to ‘0x00’ indicating failure in location update, the MS proceeds to step 314. However, if the Location Update Response field is set to ‘0x01’ indicating success in location update, the MS proceeds to step 316. In step 314, the MS performs a network re-entry procedure. In step 316, the MS performs a PG_ID update procedure by storing the newly recognized PG_ID.
As described above, according to the conventional IEEE 802.16 standard, when an MS in the idle mode moves, changing its paging group, it updates a PG_ID through an exchange of RNG-REQ/RNG-RSP messages with the serving BS. However, as the communication system evolves based on ALL IP, there is currently no specific operation method capable of performing paging when an MS in the idle mode moves, changing its IP subnet. In the IP-based wireless mobile communication system, when an MS moves, thereby changing its IP subnet, it is expected that the MS will change, register and update an IP address in a call setup process during paging. This causes a time delay due to the call setup procedure.
Furthermore, the PC or PC-controlled BSs conventionally broadcast(s) a MOB_PAG-ADV message to all MSs belonging to at least one paging group. Therefore, system resource consumption and signaling load due to the transmission of the MOB_PAG-ADV message serve as overheads for the system.